机械力化学法制备绢云母/TiO2复合颗粒材料的机理研究及表征

为提高二氧化钛颗粒的分散性、改善其颜料特性并降低其用量,同时发挥绢云母矿物的协同作用,采用机械力化学方法(mechano-chemical method,MCM),通过绢云母颗粒表面包覆二氧化钛方式制备了“核-壳”结构绢云母/TiO2复合颗粒材料,采用SEM(scanning electron microscope)、EDS (energy dispersive spectrometer)、XPS(X-ray photoelectron spectroscopy)分析方法和颜料性能测试手段,对复合粉体的微观结构和颜料性能进行了测试与表征.所制备绢云母/TiO2复合粉体白度为84.3％,遮盖力18.68 g/m2,吸油量26.79 g/100 g,绢云母/TiO2复合颗粒以绢云母表面包覆均匀、稳定的二氧化钛颗粒为特征.研究表明:绢云母/TiO2复合粉体已具有与钛白相似的使用性能,作为白色颜料可在若干应用领域实现对钛白粉的替代.     

Ni-PS-MoS2复合镀层的制备及摩擦磨损性能

用苯乙烯单体聚合反应法,在MoS2微粒表面包覆一层聚苯乙烯,经红外线光谱检测证明聚苯乙烯成功包覆在MoS2表面上.制备Ni-MoS2及Ni-PS/MoS2复合镀层试样,在镀液中微粒浓度相等的情况下,复合镀层中PS/MoS2微粒比MoS2微粒含量高.用扫描电镜观测复合镀层表面和截面彤貌,Ni-PS/MoS2复合镀层表面比Ni-MoS2复合镀层表面平整规则.在圆-盘式摩擦磨损试验机上进行复合镀层的摩擦磨损性能测试,结果表明制备工艺相同时,Ni-PS/MoS2复合镀层的摩擦学性能均优于Ni-MOS2复合镀层,镀液中微粒浓度25 g/L时,Ni-PS/MoS2复合镀层的摩擦学性能最好.     

盐酸沉淀法制备纳米SiO_2/粉煤灰微珠复合颗粒

以工业级粉煤灰微珠和模数为3.3的水玻璃溶液为原料,采用盐酸沉淀法,利用非均相形核沉积原理,在微米级粉煤灰颗粒表面包覆一层纳米SiO2颗粒.通过扫描电子显微镜、X射线衍射仪、傅里叶转换红外线光谱仪等对包覆产物进行表征,制备得到了具有"核-壳"结构的微珠/SiO2复合结构颗粒,同时SiO2包覆层是以Si-O-Si键的形式结合于微珠表面并不断生长.对这种二级结构复合颗粒进行有机疏水改性,通过"涂敷法"构建超疏水性表面,表面平均接触角为152.4°,达到超疏水性能要求.     

表面改性对非晶态CeMg12合金电化学储氢性能的影响

研究了球磨时间、氟处理、表面包覆对CeMg12+200%Ni(质量分数,下同)复合贮氢合金电极电化学性能的影响.结果表明球磨50 h后的复合电极材料的具有最大的电化学放电容量为1 209.6 mAh/g,但是电化学循环稳定性较差,10次循环保持率为37.3%;氟处理后复合电极的最大放电容量和循环稳定性同时下降;添加质量分数4%Ti进行球磨包覆后,合金的最大放电容量基本上不变,为1 049.58 mAh/g,而10次循环的保持率提高到了53.7%.另外,将复合电极置于Hg中浸泡也可以提高循环稳定性.     

粉石英包覆二氧化钛制备复合粉体的研究

采用化学沉积法在粉石英表面包覆TiO2,研究了TiOSO4—H2O—SiO2反应体系的温度、水解时间、晶种、表面活性剂等因素对包覆的影响;利用SEM,XRD,IR等对复合粉体的形貌、组成、表面官能团等进行表征.结果表明:化学沉积过程中采用自生晶种、并有表面活性剂作用下,水解温度95℃,粉石英-硫酸氧钛水溶液体系保持5 h,能制备出包覆效果良好的复合粉体,白度最高可达93.4,复合粉体中粉石英表面包覆致密的锐钛型TiO2,二者以化学键结合,强度较高.     

Fe-SiO2磁性核壳复合粒制备与表征

采用溶胶凝胶方法制备羰基铁/Si02核壳复合粒子.采用SEM、TEM、XRD、VSM、TG-DSC测试手段对材料形貌、微观结构与性能进行表征.实验结果表明羰基铁粉粒子表面均匀地包覆非晶态SiO2纳米壳层.包覆后的核壳复合粒子仍具有很好的超顺磁性能,适当控制壳层的厚度可以提高超顺磁性能.同时抗氧化性能也明显提高.     

超微金刚石对Ni-P化学复合镀层性能的影响

为改善Ni-P化学镀层的性能,采用化学复合镀的方法在镀层中添加了爆轰合成超微金刚石(Ul-trafine Diamond,UFD).研究了复合镀层的形成机理及镀液中UFD含量对复合镀层显微硬度及耐磨性的影响规律.实验用UFD众数粒径为114.6 nm.镀层显微硬度采用国产71型显微硬度仪进行检测,耐磨性采用国产MM200型磨损试验机进行检测.结果表明:随着镀液中UFD的加入,Ni-P合金粒子会以UFD颗粒为核心形成硬度较高的"包覆球"."包覆球"沉积到镀件表面形成复合镀层.复合镀层的显微硬度及耐磨性均随镀液中UFD含量的不同呈规律性变化.与Ni-P化学镀层相比,当镀液中UFD含量为0.8 g/L时,复合镀层显微硬度可提高0.6倍;当镀液中UFD含量为1.0 g/L时,复合镀层耐磨性可提高4.8倍.     

硅-铁均匀包覆型复合粉的制备方法

为了实现质量分数6.5%Si-Fe合金的直接轧制成型,需要首先获得具有塑性变形能力的硅-铁均匀包覆型复合粉.探索了利用混合球磨技术制备硅-铁均匀包覆型复合粉的方法.利用电子探针分析了不同球磨条件下,Si、Fe元素分布及Fe颗粒的变形程度.结果表明:当球料比5:1、转速350 r/min、球磨2 h时,可以获得Si均匀包覆于Fe表面、并且Fe颗粒不变形的Si-Fe包覆型复合粉.     

C包覆CoMoO_4复合纳米片阵列材料的制备和赝电容性能的研究

采用两步水热法,结合高温煅烧工艺,制备了直接生长在泡沫Ni基底上的C包覆CoMoO_4复合纳米片阵列材料。利用X射线衍射仪(XRD)、能谱仪(EDS)和场发射扫描电子显微镜(SEM)分析C包覆CoMoO_4的结构特征,结果表明C成功包覆在多孔交联CoMoO_4纳米片的表面。通过循环伏安法和恒流充放电法分析C包覆CoMoO_4的电化学性能,发现C包覆显著提高CoMoO_4的比电容和循环性能。在1A/g的电流密度下循环2000次,最高比电容达1864.79F/g,比电容保持率86.65%。比电容和循环性能的改善是由于碳包覆提高了CoMoO_4电导率和结构稳定性,促进了赝电容反应。     

ZrO_2包覆对LiNi_(0.8)Co_(0.2)O_2结构和性能的影响

为提高锂离子电池正极材料LiNi_(0.8)Co_(0.2)O_2的综合电化学性能,采用高温固相法对其表面进行ZrO_2包覆。以X射线衍射、扫描电子显微镜、电化学阻抗和电化学充放电等方法对材料进行表征。结果显示,ZrO_2可均匀分布在LiNi_(0.8)Co_(0.2)O_2表面而不影响其晶体结构,但对电化学性能影响明显,即首次放电容量略有降低,由168.25 mAh/g降到157.43 mAh/g;1C、2C倍率性能有较大改善,循环性能的提高尤其突出,在100周循环内,LiNi_(0.8)Co_(0.2)O_2的容量保持率从90.68%提高到97.70%。其原因是:(1)包覆层有效避免了电解液与正极材料直接接触、抑制副反应的发生;(2)包覆过程中生成的Li_2ZrO_3提高了材料的离子导电性。该研究结果为改善锂离子电池正极材料综合电化学性能提供了简便、有效的方法。     

Solidification/Adsorption of Heavy Metals by FA/FA-MSWI based Al-Substituted Tobermorite

Fly ash(FA) was utilized to hydrothermally synthesize FA based Al-substituted tobermorites, and was combined with raw materials of FA and municipal solid waste incineration fly ash(MSWI) to hydrothermally synthesize FA-MSWI based Al-substituted tobermorites. Then optimum samples named FA-T and FM-T were selected, correspondingly. Their intrinsic properties as well as their solidification/stabilization and adsorption of heavy metals were studied. The experimental results showed that the specific surface area of FA-T and FM-T was 28.259 m~2/g and 45.939 m~2/g, respectively. Their pore size distribution, particle size distribution, and median particle size were approximately the same. FA-T and FM-T both had great potential of solidification/stabilization heavy metal to dispose hazardous solid waste. Further, FA-T and FM-T also showed good adsorption efficiency for heavy metals Pb~(2+) and Cu~(2+) as adsorbent to treat waste water.     

Damping properties of fly ash/epoxy composites

An inexpensive fly ash (FA), which is from a waste product, was employed to prepare fly ash/epoxy composites. The purpose of this study is to characterize the contributions of matrix viscoelasticity, hollow structure characteristic (porosity), and filler/matrix interface friction to the high vibration damping capacity of such composites. The damping properties of the composites were investigated in the temperature range of -40 to 150°C and in the frequency range of 10 to 800 Hz by using a tension-compression mode. The results indicate that the peak value of damping loss factor (tanδ) for the fly ash/epoxy composites can reach 0.70-0.90 in test specification, and the attenuation of damping loss factor is inconspicuous with increasing frequency. In addition, scanning electron microscope (SEM) was used to observe the morphology of the fly ash as well as its distribution in the matrix, which will help to analyze the effect of fly ash on the damping properties of the fly ash/epoxy composites.     

Microstructural characterization and mechanical property of Fly Ash/Al-25Mg composites

Fly ash/Al-Mg composites are fabricated by powder metallurgical method. The morphology and structure of fly ash/A l-Mg composites are characterized by scanning electron microscope （SEM） and X-ray diffraction, respectively. The influences of different fly ash content on the friction and wear behavior of the composites are investigated at a constant sliding velocity of 400 r/min and the worn mechanism of composites is discussed. The results indicate that the friction coefficient is steadily lower than that of Al alloy matrix at the lower fly ash content and loads. For the fly ash/Al-Mg composites, the wear mechanism is characterized as abrasive wear and adhesive wear under small normal load and at low fly ash content, and it is characterized as delamination wear and abrasive wear transferred onto the counterpart under high normal load and at high fly ash content.     

Utilization of thermally treated flue gas desulfurization (FGD) gypsum and class-C Fly Ash (CFA) to prepare CFA-based geopolymer

The feasibility of utilization of flue gas desulfurization (FGD) gypsum and Class-C fly ash (CFA) to prepare CFA-based geopolymer were studied. The results showed that geopolymer made from 90% CFA and 10% FGD gypsum (FGDG) which was thermally treated at 800 ℃ for 1 h obtained the better compressive strength of 37.0 MPa. The micro characteristics and structures of the geopolymer samples of CFA and CFA-FGDG were tested by XRD, FT-IR, and SEM-EDXA after these samples cured at 75 ℃ for 8 h followed by 23 ℃ for 28 d. Both the geopolymer samples of CFA and CFA-FGDG have significant asymmetric stretching of Al-O/Si-O bonds and Si-O-Si / Si-O-Al bending band. In geopolymer sample of CFA-FGDG, a small quantity of lathy products probably being the ettringite wrapped over the spherical fly ash particle, and the concentration of sulfur is much more than that in geopolymer sample of CFA. It is indicated that FGD gypsum may react during alkali-activated and geopolymeric process.     

PVA纤维水泥基材料力学性能试验研究

为了制备超高韧性的水泥基复合材料(ultra high toughness cementitious composites,UHTCC),通过抗压、抗折以及直接拉伸试验,结合扫描电镜(SEM)测试,探讨粉煤灰掺量、石英砂掺量对UHTCC力学性能的影响;通过粉煤灰-石英砂复配,研究超高韧性水泥基材料的最优粉煤灰-石英砂掺量配比.结果表明:随着粉煤灰掺量的增加,抗压、抗折强度降低,拉伸变形增大,但是当粉煤灰质量/水泥质量(m(FA)/m(C))大于2.7后,拉伸变形提高缓慢;当石英砂质量/胶凝材料的质量(m(S)/m(B))为0.36时,拉伸变形性能最好;本文确定的最优粉煤灰-石英砂体系掺量为:m(FA)/m(C)-m(S)/m(B)=1.2-0.48,m(FA)/m(C)-m(S)/m(B)=2.2-0.36.     

Compressive Strength, Pore Size Distribution and Chloride-ion Penetration of Recycled Aggregate Concrete Incorporating Class-F Fly Ash

The effects of fly ash on the compressive strength, pore size distribution and chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mb：tures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/ m^3 , respectively. The concrete rnixtures in series II had a water-to-binder ratio and a cement content of 0.45 and 400 kg/ ml respectively. Recycled aggregate was ased as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In cutdition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased us the recycled aggregate content increased. Furtherrruore , an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ush improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.     

Static and dynamic leaching experiments of heavy metals from fly ash-based geopolymers

The feasibility of high calcium fly ash (CFA)-based geopolymers to fix heavy metals were studied. The CFA-based geopolymers were prepared from CFA, flue gas desulfurization gypsum (FGDG), and water treatment residual (WTR). The static leaching showed that heavy metals concentrations from CFAbased geopolymers were lower than their maximum concentration limits according to the U.S. environmental protection law. And the encapsulated and fixed ratios of heavy metals by the CFA-based geopolymers were 96.02%–99.88%. The dynamic real-time leaching experiment showed that concentration of Pb (II) was less than 1.1 μg / L, Cr (VI) less than 3.25 mg / L, while Hg (II) less than 4.0 μg / L. Additionally, dynamic accumulated leaching concentrations were increased at the beginning of leaching process then kept stable. During the dynamic leaching process, heavy metals migrated and accumulated in an area near to the solid-solution interface. When small part of heavy metals in “the accumulated area” breached through the threshold value of physical encapsulation and chemical fixation they migrated into solution. The dynamic leaching ratios and effective diffusion coefficients of heavy metals from CFA-based geopolymer were very low and the long-term security of heavy metals in CFA-based geopolymer was safe.     

Experimental studies on the erosion rate of different heat treated carbon steel economiser tubes of power boilers by fly ash particles

The experimental investigations on the effect of the fly ash particle size,velocity,impingement angle,and feed rate were done with an emphasis on the effect of erosion on annealed SA 210 GrA1(A) and normalized SA 210 GrA1(N) carbon steel economizer-tube materials.Erosion rates were evaluated with different impingement angles ranging from 15° to 90°,at four different velocities of 32.5,35,37.5,and 40 m/s,and at four different feed rates of fly ash particles of 2,4,6 and 8 g/min.The erodent used was fly ash p...     

粉煤灰分子筛的制备与性能研究

本实验采用碱熔融水热法,以预处理过的粉煤灰为主要原料,以固体NaOH为助溶剂制备性能稳定的沸石分子筛．研究了NaOH与粉煤灰比、煅烧温度、晶化时间、晶化温度等实验因素对合成沸石结构和性能的影响,利用x射线衍射（XRD）、扫描电镜（SEM）、比表面积（BET）、分光光度计,分别对晶型、表面形貌和吸光度进行了表征．实验结果表明：当NaOH与粉煤灰比为1．3、煅烧温度为600℃、晶化时间为10h、晶化温度为100℃条件下合成的沸石分子筛是Na—A型,BET测定其比表面积是97．053m2,g,2h内亚甲基蓝的去除率可达97％,具有良好的吸附性能．     

粉煤灰脱除烟道气SO2实验

以粉煤灰作为脱硫剂，采用固定床反应器，以模拟烟道气对粉煤灰的脱硫性能进行了研究，结果表明，在粉煤灰加入量为120g、含水率20％左右，对烟气流量为4L／min、SO2浓度为0．2％(体积浓度)的模拟烟道气脱硫效率可达最佳水平，脱硫率维持98％的时间可达到6min．粉煤灰对低浓度的二氧化硫脱硫效果较好，即比较适合用于锅炉烟道气脱硫．